The freemium business model, which supports a free to download app through optional in-app purchases, is currently dominating the world of mobile games. In-app purchases accounted for 98 per cent of Google Play revenue in November 2013, according to Distimo.

With those kinds of figures, its no surprise that more and more developers are releasing freemium games. But what happens when a previously paid game tries to change its business model after release?

Thats a question that has been raised after Tiny Thief, an Android and iOS game published by Rovios third-party Stars initiative, dropped its original pricetag of $2.99/£1.99 and became a free download. But while this may be great news for people who hadnt played the game yet, its a different matter for those who have already bought it.

As spotted by Android Police, the app has updated to introduce in-app purchases to unlock extra levels which were included in the original paid version, as well as advertising. Its presumably possible to block the update, if the user knows whats coming – or, as Android Police illustrates, to request a refund – but its likely to alienate the games existing audience. Nevertheless, Id be surprised if we didnt see more cases like this in the coming months, as developers try to cash in on the opportunities presented by freemium apps.